Director array for antennas

ABSTRACT

A parasitic director array for use with active dipole sections of an antenna. In antennas having a relatively broad operating frequency range which may be of the order of 2:1 (i.e., wherein the operating frequency of the high end of the range is two or more times as great as the operating frequency at the low end of the range). The director array which is comprised of at least first and second conductive plates arranged in closely spaced fashion and staggered along the antenna mounting rod so that the conductive plates extend on opposite sides thereof operate as individual director elements near the high end of the operating band, while operating effectively as a single director element near the low end of the band so as to improve directivity and gain characteristics over the entire operating frequency band of the antenna active element region.

[63] Continuation of Ser. No. 23,232, March 25, 1970 United StatesPatent [191 Grant I DIRECTOR ARRAY FOR ANTENNAS [75] Inventor: Ronald D.Grant, Urbana, ll].

[73] Assignee: JFD I Electronics Corporation,

Brooklyn, N.Y. [22] Filed: Dec. 3, 1971 [21] Appl. No.: 204,486

1 Related US. Application Data abandoned. I

52 U.S.Cl.... ..343/815,343/915 51 Int. Cl. ..ll01q21/12 [58]FieldoiSearch ..343/8l5,819

[56]- g l Refer ences Cited UNITED STATES PATENTS 3,344,431 9/1967Greenberg et al ..343/8 1 8 3,440,658 4/1969 Bogner Winegard et a]...343/8l5 Apr. 10, 1973 Primary Examiner-Eli Lieberman [5 7 ABSTRACT Aparasitic director array for use with active dipole sections of anantenna. In antennas having a relatively broad operating frequency rangewhich may be of the order of 2:1 (i.e., wherein the operating frequencyof the high end of the range is two or more times as'great as theoperating frequency at the low end of the i range). The director arraywhich is comprised of at least first and second conductive platesarranged in closely spaced fashion and staggered along the anten namounting rod so that the conductive plates extend on opposite sidesthereof operate as individual director elements'near the high end of theoperating band, while operating effectively as a single director elementnear the low end of the band so as to improvev directivity and gaincharacteristics over the entire operating frequencyband of the antennaactive element region.

12 Claims, 12 Drawing Figures ml ml] an, @44

ElHE-lE-l' PATENTEBAPR 01973 727, 232

SHEET 1 [IF 4 PATENTED APR] 0197:

SHEET l 0F 4 DIRECTOR ARRAY FOR ANTENNAS This is a continuation ofapplication, Ser. No. 23,232, filed Mar. 25, 1970, now abandoned.

The present invention relates to antennas and more particularlyto adirectorarray for usewith antenna active element arrays to improve thedirectivity and gain characteristics over the entire operating frequencyband in which the frequency at the high end of the band is two or moretimes as great as the frequency at the low end of the band. i

There exists a wide variety of antennas capable of providing reasonablygood gain'and directivity characteristics over a substantially largeoperating frequency range. For example, it is well known to employYagitype antennas and logperiodic type antennas for television receptionsince such antennas have characteristics of providing reasonably goodgain and directivity characteristics over substantially broad operatingfrequency bands. The television frequency ranges consist of low band VHFwhich extends from 54-88 megacycles; the upper VHF band which extendsfrom 174-216 megacycles; and the UHF band which extends from 470-890megacycles. Numerous efforts have been made to improve gain anddirectivity characteristics of such antennas. One typical approach isthat of providing parasitic arrays comprised of one or more parasiticelements of either the director or reflector type which may either beinterspersed amongst the active elements or, alternatively, placed infront of the front end of an active element array. Also, both techniqueshave been incorporated .within an individual antenna array.

One prior art array which has been employed to improve gain anddirectivity characteristics is comprised of one or more conductiveplates arranged at substantially equal spaced intervals along theantenna mounting rod and in front of the front end of the antenna activeelement array. These elements, in one preferred form, are comprised ofsubstantially circular shaped discs formed ofa conductive material andwhose dimensions are selected to cause the individual conductorplates tooperate as director elements for the purpose of improving the radiationpattern and hence the gain and directivity characteristics of theantenna. This technique has been employed withsome success for use withantennas designed to receive television signals within the UHF range.The dimensions of such conductor plates and their interval spacing havebeen found to be rather critical in that the interval spacing betweenadjacent elements have been found to control the effectiveness of "theseelements over the operating frequency band; The dimensions of theconductor plates have also been found to control the effectiveness ofthe director elements to a very significant degree.

For example, it has been found that the closer spacing of the conductiveplates results in improved gain toward the high end of the operatingfrequency band. Likewise, the dimensions (i.e., diameters) of theindividual conductive plates control the effectiveness of the directorelements such that the elements of decreased diameter operate moreeffectively near the high end of the operating frequency band while theincreasing diameter of the elements cause greater effectiveness nearthelower end of the operating frequency band. r

Still further investigation of director dimensioning and spacing hasshown that it is a practical impossibility to design a director arraywhich is capable of improving to the same degree the radiation patternover the entire operating frequency range. As a result of this, thedesign of such a director array becomes a compromise wherein the spacingbetween director elements and the dimensions (i.e., size) of thedirector elements themselves are normally chosen so as to yield thegreatest improvement in radiation pattern at an operating frequencywhich lies slightly above the middle range of the operating frequencyband. For example, in antennas designed for UHF reception whoseoperating frequency range extends from'470-890 megacycles, it hasbeenfound to be most preferable to dimension andspace the directorelements so as to yield the optimum improvement in the antenna radiationpattern at an operating frequency in the immediate region of about 800megacycles. Experimentation has shown that the deterioration of theradiation pattern decreases for operating frequencies between the midrange and thehigh end of the operating' frequency band. Deteriora tionin the improvement of the radiation pattern from the mid range value tothelow end of the operating frequency bandoccurs at a much moresignificant rate. Although the obvious adjustment of director elementand interval spacing to provide optimum improvement in the radiationpattern at a frequency well below mid range has been attempted,experimentation of antennas utilizing this design approach has shownthat the deterioration in the radiation pattern begins to drop offrapidly so that the TV reception at the high end of the operatingfrequency band is substantially affected by this design change resultingin the use of director arrays employing the design criteria firstdescribed hereinabove.

The present invention is characterized by providing a director array foruse with antenna active element sections which is capable of'pr'ovidingsignificant improvement in the radiation pattern of the antenna oversubstantially the entireopera'ti'ng frequency band as compared withantennas employing conventional director arrays of the type describedhereinabove.

Whereas the director array of the present invention,

whose arms. are either stright or Veed and whose dipole arms and spacingbetween adjacent dipoles decreases in log-periodic fashion from the rearof the array toward the front. The active element section is preferablymounted upon on (or in some cases, two) mounting rod, the forward end ofwhich (or an extension thereof) supports the director array. Preferably,the antenna feed point for connection to a receiver (or transmitter) iscoupled to the active element section by means of a feeder harness. Thefeeder harness is preferably transposed between adjacent-dipole elementswithin the array. I

The director elements are mounted upon the front end of the antennaarray in front of the feed point such that the director elements extendin alternating fashion to opposite sides of the principal axis and liesubstantially in a horizontal plane and are further substantiallycoplanar with the antenna active elements. As an alternative arrangementthe director elements may alternately extend above and below theprincipal axis and yield good operating results. The top-bottomalternation also works well. The spacing intervals between adjacentconducting plates and the dimensions of each plate are chosen so as toprovide a substantially optimum radiation patter in the vicinity of 890megacycles which lies at the top end of the UHF operating band. Theoperating characteristics of the director array are such that near thehigh end of the operating frequency band each of the director elementsare spaced by a distance sufficient to cause each of the elements tooperate as separate elements which appear as two separate rows of smallparasites. When the antenna is operating in the low frequency mode,adjacent staggered conductive plates operate effectively as a singleconductive platev which gives the effective characteristic of appearingas a single slightly tilted and larger conductive member. Thus, thedirector array provides an improved radiation pattern over substantiallythe entire UHF operating frequency band as compared with conventionaltechniques in which conductive plate director arrays are capable ofimproving the radiation patterns over only a small portion of the entireUHF frequency band. For example, the improvement in gain has been foundto be double that of the conventional design. 7

It is therefore, one object of the present invention to provide a noveldirector array comprised of a plurality of staggered conductive platesarranged at the front end of an antenna active element section whereinthe spacing interval between conductor plates and the dimensions of theplates themselves act to provide significantly improved radiationpatterns over the entire operating'frequency band.

This, as well as other objects of the present invention will becomeapparent when reading the accompanying description and drawings inwhich:

F IG, 1a is a top plan view of one preferred conductive plate which maybe employed in the director array of the present invention.

FIGS. 1b and 1c are side and end views respectively of the conductiveplate of FIG. la.

FIG. 2 is a plan view showing an alternative preferred embodiment of aconductive plate which may be employed with equal success in thedirector array of the present invention. FIGS. 2b and 2c are side andend views respectively of the conductive plate of FIG. 20.

FIG. 3a shows a top plan view of an antenna array employing a directorarray designed in accordance with the principles of thepresentinvention.

FIG. 3b shows an elevational view of the antenna array of FIG. 3a.

FIG.- 4a shows a top plan view of another antenna array employing thedirector array of the present invention.

FIG. 4b is an elevational view of the antenna array shown in FIG. 4a.

-conductive sheet 11 (preferably aluminum) having tapered sides 12 and13, which curved sections are truncated at 14. The sides 12, 13 and 14terminate in a continuous flange 15, shown best in FIG. 1b. The majorportion of plate 11 is provided with a 17 shaped reinforcing rib 16. Asquare shaped slot 17 is formed at the inward end of plate 10 forjoining to the antenna supporting rod in a manner to be more fullydescribed.

A pair of C-shaped openings 18 and 19 are formed near the inboard end ofplate 10 and the portions of 11a and 1117 (see FIGS. lband 10) definedby the openings are bent inwardly in the manner shown best in FIG. 10 toform a pair of mounting arms each provided with an aperture 19a and 19brespectively, for receiving a fastening member (not shown in FIGS.la-1c)'to firmly secure each plate to the antenna supporting rod.

FIGS. 2a-2c show an alternative conductor plate emobdiment 20 formed ofa substantially thin sheet 21 of conductor material (preferably aluminumwhich sheet has a substantially rectangular shape. The outboard endthereof is provided with a C-shaped reinforcing rib 22, while thecentral portion thereof is provided with a substantially rr-shapedreinforcing rib 23. The top and bottom sides 24 and 25 each terminate ina downwardly depending flange 24a and 25a respectively, to furtherreinforce the plate.

' A substantially square shaped slot 26 is provided at the inboard endof conductive plate 20 to embrace the antenna supporting rod in a mannerto be more fully described. A pair of C-shaped openings 27 and 28 areprovided near the inboard end of the conductor plate and the plateportions 21a and 21b defined by these openings are bent downwardly inthe manner shown best in FIG. 2c to form a pair of mounting arms eachprovided with openings 29a and 29b, respectively, for receivingfastening means (not shown in FIGS. 1alc) for the purpose ofsecuring theconductive plate to the a director array which may utilize theconductive plates 10 or 20 described hereinabove. The antenna array 30is comprised of a VHF section 31, a UHF section 32 and a director array33.

The VHF section is comprised of a pair of elongated conductivesupporting members 34 and 35 mechanically joined to one another andelectrically insulated from one another by mounting brackets 36a-36c.These brackets maintain members 34 and 35 in spaced parallel fashion asshown best in FIG. 3b. A U-bolt assembly 37 is firmly secured to members34 and 35 and is provided for the purpose of mounting the antenna to asuitable vertically aligned supporting mast.

The VHF section 31 which is designed to receive (or transmit) televisionsignals lying in both the low band and high-band VHF is comprised of aplurality of dipole elements 38a-38b through 4la-4lb which are ofelectrical lengths and are arranged at spaced intervals selected toprovide optimum and preferably substantially uniform gain over both lowband and'high band VHF. Each of the dipole elements is mounted to anassociated one of the conductive members 34 and 35 by bracket means42a-42g. These brackets electrically connect their associated dipolearms in alternating fashionto members 34 and 35 which thereby act as theequivalent of a transposed feeder harness. Each of the elements hasassociated therewith an arrow such as, for example, arrow 43 whichindicates the direction in which its associated dipole arm may be foldedtoward members 34 and 35 to reduce the overall antenna size duringshipment. These arms are then unfolded in the reverse direction so as toassume the solid line positions shown in FIG. 3a.

Thedipole arms a-4lb utilize capacitive elements 44a-44 respectively,for the purpose of improving reception over the entire VHF operatingfrequency bands. These capacitive elements are described in greaterdetail in copending application, Ser. No. 523,447, filed Jan. 27, i966and assigned to the assignee of the present invention. Since a detaileddescription is set forth in this copending patent application of suchstructures will be set forth herein for pur' poses of simplicity.

The VHF section 31 is further provided with parasitic structures41a-4lb, 45a-45b and 46a-46b which parasitic structures are provided forimproving the radiation pattern of the antenna during VHF reception (ortransmission). The elements 45a and 451) are secured by means of abracket 47 to a shortsupporting arm 48 secured between elongated members34 and 35 l by means of supporting bracket 36a and a second bracket 49..The structures 46a 46b and 4la-4lb are mounted by brackets 50 and 51 toan elongated rod 52 positioned between elongated members 34 and 35 andsecured in this position by the supporting brackets 36b 7 and 360,respectively. All of the parasitic elements within the VHFsection areelectrically insulated from the array activeelements and areprovidedsolely for the purpose of improving the directivity characteristics ofthe antenna. These elements are likewise capable of being foldedinwardly toward the antenna principal axis to facilitate handling of theantenna during assembly, shippingand mounting thereof.

The UHF section 32 of antenna array 39 is comprised of a plurality ofwire elements 53a-53b through 58a-58 which form a UHF section of activeelements electrically joined to one another by means of a transposedfeeder harness 59 whose take-off point is at terminals 59a and 59b. Thespacing and electrical length of the active dipoles 53a-53b through58a-58b is such as to provide high and substantially uniform gain overthe entire UHF range. .As can best be seen in FIG. 3b, the transposedfeeder harness 59 has its separate lines 59c and 59d'electricallycoupled to the right-hand most ends of elongated conductive members 34and 35 and are secured thereto by suitable fastening means 60a and 60b,respectively. As was previously described, the conductive members 34 and35 effectively act as a transposed feeder harness, a detaileddescription of which is set forth inUQS. Pat. No. 3,108,280 and is shownbest in FIG. 2 thereof.

As can best be seen in FIG. 3b the feed point of the transposed feederharness may be provided with butterfly type fasteners such as 61 tofacilitate connection of the down-lead from the antenna to the receiver(or secured toand electrically insulated from the supporting rod 52 bymeans of substantially similar brackets 64a-69.

The design of both the UHF and VHF sections are preferably of thelog-periodic type which design is described in detail in the abovementioned US. patents and copending application and will not bedescribed herein for purposes of simplicity, however, it should beunderstood that the director array 33, to be more fully describedherein, may be utilized. with other VHF and UHF sections or with UHFsections alone which active element sections may be of any suitabledesign.

The director array 33 is comprised of a plurality of conductive platessuch as, for example, plates 10a10h each of which is substantiallyidentical in configuration to the plate 10 shown in FIGS. 10-10. As canclearly be seenfrom FIG. 3a, plates Ion-10h are arranged in staggeredfashion so that alternating plates 10a, 100, 10a

and 10g each extend toward one side of supporting rod 52 while theremaining plates 10b, 10d, 10fand 10h are interspersed amongst plates10a, 10c, l0e and 10g and extend to the opposite side of supporting rod52. Each of the plates is positioned relative to supporting rod 52(which preferably has a rectangular cross-sectional configuration) sothat their inboard slots 17 (see FIG. la) embrace rod 52, enabling tehsupporting arms 11a and 11b to be secured to the upper and lowerhorizontal surfaces of the supporting rod by fastening means 64.

In operation, the director array 33 is designed to significantly enhancethe reception (or transmission) characteristics of the antenna Ull-IFsection over'substantially the entire UHF range (470-890 megacycles).The intervals between conductive plates l0a-l0h are selected to besubstantially small and these intervals are no greater than 1/10)wherein X is the wavelength of the uppermost frequency of the UHF bandwhich is usually of the order of 890 megacycles. The closest spacinginterval is preferably no smaller than M20. The dimensions, shape andthickness of the conductive plates are adjusted to be resonant atapproximately 900 MC or the top of the UHF band. Preferably, each of theconductive plates is identical in size and configuration although somedeviation may be made for purposes of trimming the antenna design tooptimize the radiation pattern over the entire UHF range. As waspreviously described, the maximum limit of the relatively close spacingintervals between adjacent conductive plates is sufficient to cause eachplate to operate effectively as a single conductive plate at the upperend of the UHF range. Spacing much smaller than M20 will cause ad,

jacent pairs of plates such as, for example, pair 103 and 10h to operateas a single conductive plate whose effective electrical length will betoo large and therefore ineffective at the upper end of the UHF range.

By limiting the maximum amount of spacing between adjacent plates, theoperation of the director array near the low end of the UHF range issuch as to cause adjacent pairs of plates'such as plates 10g and 10h,for example, to operate effectively as a single conductive plate whoseelectrical length is proper at the lower end of the UHF band to optimizethe radiation pattern in this range. Any larger spacing would renderadjacent conductive plates incapable of operating effectively as asingle conudctive plate and thereby greatly deteriorate theeffectiveness of the director array.

FIGS. 4a and 4b show a somewhat modified antenna array 70 comprised ofaVHF section 71, a UHF section 72 and a director array 73. Similarelements as between the embodiment FIGS. 4a-4b and 3a-3b are designatedby like numerals. For example, the VHF section includes a pair ofelongated conductive elements 34 and 35 joined together by supportingbrackets 36a-36c and being further provided with a U-bolt assembly 37for mounting upon an antenna supporting mast. The VHF section isprovided with a plurality of dipole arms 740-74 through 76a-76brotatably mounted by suitable brackets 77a-77 f to selective ones of'theelongated conductive members 34 and 35 which operate as a transposedfeeder harness in the same manner as was previously described. Inaddition to electrically connecting the dipole arms to elements 34 and35 these brackets permit folding of the arms toward the principal axisof the antenna in the direction shown by the arrows immediately adjacentthe outboard ends of each arm. For example, arrow 78 indicates that arm76a folds counterclockwise relative to its bracket 77e while arm 75afolds clockwise as shown by arrow 75 to align with the principal axis ofthe antenna array.

When the dipole arms are folded outwardly to their proper position, asshown in solid line fashion in FIG. 4a, it can be noted that the VHFsection is comprised of dipoles whose arms are Veed forward toward thefront end of the antenna.

It should be noted that arms 75a-76b are provided with capacitiveelements-78a-78d, respectively, which capacitively couple the inboardand outboard sections of the dipole arms for improving the overall gainof the antenna throughout the entire VHF upper and'lower band. The VHFsection 71 is further provided with a parasitic structure comprised ofarms 79a and 79b joined at their inboard ends by means of a bracket 80to supporting rod 52 which, in turn, is positioned between elongatedmembers 34 and 35 and is supported in this position by means of brackets36b and 36c. The parasitic structure 79a-79b is provided with capacitiveelememts 782 and 78f, respectively, which operate in a manner similar tothe capacitive elements 78a-78d in that the inboard and outboardsections of arms 79a and 79!) are either loosely or tightly(electrically) coupled to one another, depending upon the operatingfrequency of the antenna at any given moment.

The UHF section 72 of antenna array 70 is comprised of a plurality ofwire-type arms or elements 80 1-80 through 85a which are arranged instaggered fashion on opposite sides of the antenna principal axis andare selectively connected to the upper and lower elongated arms 34 and35 in a staggered fashion so as to utilize the arms 34 and 35 as aneffective transposed feeder harness in the same manner as these arms areutilized in .the VHF section 71 and in the VHF section 31 of antennaarray 30 shown in FIG. 3a. The feed point for the active element arraysis at the front end of the UHF array 72 and is electrically coupled bysuitable conductors 86 to a bracket 87 provided with butterfly fasteners88 for coupling the feed point to a receiver (or transmitter) facilitynot shown in the figures. The spacing intervals of the dipole arms andthe length of the dipole arms in both the VHF section 71 and UHF section72 are in accodance with log-periodic design described in any of theabove mentioned copending applications and U.S. patents in order toenhance the gain of the antenna over both the low band and high band VHFand the UHF ranges.

Supporting arm 52 extends forward of the feed point connectors 88 andhas coupled thereto a plurality of conductive plates 20a-20f which may,for example, be of the type shown as conductive plate 20 in FIGS. 2a2c.The conductive plates are arranged along the forward end of supportingarm 52 in a staggered fashion wherein plates 20a, 20c and 20e extend toone side of the antenna princioal axis while plates 20b, 20d and 20fextend to the opposite side of the principal axis. The slots 26 (seeFIG. 2a) of each conductive plate are positioned to surround supportingrod 52 which preferably has a rectangular shaped cross-sectionalconfiguration. The mounting arms 21a and 21b (see FIGS. 4a, 4b, 2b and2c) are secured to the upper and lower surfaces of supporting rod 52 bysuitable fastening means 8-9.

All of the conductive plates are substantially identical in size andconfiguration although some departure from this design may be employedto optimize the operating characteristics of the antenna array. Thespacing intervals and dimensions of the conductive plates are selectedin the manner previously described so as to enable adjacent pairs ofconductive plates, for example, plates 20e and 20f, to operateeffectively as a single conductive plate near the low end of the UHFrange while operating as individual conductive plates near the upper endof the UHF range so as to provide significantly improved radiationpatterns over the entire UHF range. In operation near the high end ofthe UHF range the conductive plates operate effectively as two pairs ofarrays (one array comprised of conductive plates 200, 20c and 202 andthe other array being comprised of plates 20b, 20d and 20f) each ofwhich is spaced apart sufficiently to allow each plate to operateindependently of every other plate to enhance the operatingcharacteristics of the antenna. Near the low end of the UHF range theplates are spaced closely enough and are individually dimensioned sothat each pair of adjacent plates, for example, plates 20e and 20f,operate effectively as a single conductive plate whose dimensions aresuch as to enhance the operating characteristics of the antenna in thelow end of the UHF range.

FIGS. 5 and 6 show additional preferred embodiments of the conductiveplates which may be employed with equal success in the antenna arrayspreviously described. The embodiment 90 of FIG. 5 is comprised of aconductive plate having a tapered outboard end 91. The bent portions 92and 92a form the mounting arms as was previously described.

The conductive plates 93 of FIG. 6 is a truncated circular configurationwherein less than half of the entire circle is removed. The arms 94 and94a which act as the supporting arms, are pivotally mounted to thesupport 95 to enable each conductive plate to be pivoted inwardly towardthe supporting arm to reduce the overall volume of space required forstripping the antenna. When installing the antenna the plates arepivoted outwardly to assume their operating position.

The forward ends of arms 94 and 94a are tapered to cooperate with a pairof ears 96 and 96a projecting slightly upwardly from and integrallyformed with a small metallic plate 97, wherein like plates are mountedon opposite surfaces of support 95. Each of the pair of ears 96 and 96adefine a gap 98 the'rebetween. By rotating the truncated disc 93 in adirection shown by arrow 99, the tapered forward end of arms 94 and 94asnap into position in the gap 98 formed between the slightly upwardlybent cars 96 and 96a so as to lock the truncated disc 93 in positionwhereby the disc is oriented at an angle of substantially 90 relative tosupport 95.

[team be seen from theforegoing description that the present inventionprovides a novel director array for use with UHF or combined UHF-VHFantenna arrays in which the director elements are arranged in staggeredfashion on opposite sides of the antenna array principal axis and are sospaced and dimensioned as to enhance the operating characteristics overthe entire UHF operating range by a significant amount as compared withconventional techniques. Although the antenna array 30'is described asemploying conductive plates of the type'shown in FIG. 1a, and theantenna array 70 is described as employing conductive plates of the typeshown in FIG. 2a, it should be understood that either type of conductiveplate may be used in either array. Also, the arrays may be employed withthe UHF arrays alone. It should further be understood that'a lesser orgreater number of conductive plates may be employed in thedirector arrayas long as a minimum of at least two such director elements eachextending to opposite sides of the antenna array principal axis areemployed so as to enhance the operating characsive privilege or propertyis claimed are defined as follows:

l. A director array for use in antennas having an ac- The embodiments ofthe invention in which an exclutive element section mounted along aprincipal axis and designed to operate overa predetermined frequency ngsaid active element section having a feed point coupled to a feederharness at the front end of said active element section, said feederharness coupling all of the active elements to said feed point, theactive elements lying substantially within a plane; said director arraybeing positioned in front of said active section and said feed point andbeing comprised of mounting means axially aligned with the principalaxis of said active element section, andat least first and secondsubstantially flat conductive plates secured to said mounting means andextending in diametrically opposite directions from the principalaxis ofsaid active element section and arranged in staggered spaced parallelfashion, said conductive plates being substantially mirror images of oneanother relative to an imaginary plane of symmetry passing through saidprincipal axis and the planes of said plates being perpendicular to theplane in which said active elements reside; the spacing between adjacentplates being in the range from no greater than )t/IO to no less than)t/2O where )r is the wavelength corresponding to the highest frequencyof the operating frequency range.

2. The director array of claim 1 wherein said conductive plates are eachtuned to resonate at a frequency near the high end of said operatingfrequency range and being spaced no closer than M20 wavelengths apartwhere A is the wavelength of the upper end of said frequency range.

3. The director array of claim 2 wherein said conductive plates arespaced apart no greater than M1 0.

4. The director array of claim 3 wherein said conductive plates are eachtuned to resonate at a frequency near the high end of said operatingfrequency range and being spaced no closer than M20 wavelengths apartwhere A is the wavelength of the upper end of said frequency range. W

5. The director array of claim 1 further comprising a support arm forsupporting said conductive plates:

each of said conductive plates being provided with a pair of mountingarms for pivotally mounting said conductive plates to said support arm;V

at least one of said mounting arms having a tapered forward end;

a pair of slightly upwardly bent ears being provided along said supportadjacent one of said arms and defining a gap therebetween to embrace theforward tapered end of said one of said mounting arms and thereby locksaid conductive plate in the row end of the tapered plates projectsoutwardly from said support.

9. Thearray of claim 1 wherein said plates are arranged in alternatingfashion to lie respectively above and below said principalaxis.

10. The array of claim 1 wherein said plates are arranged in alternatingfashion to lie respectivelyto the left and to the right of saidprincipal axis.

11. A director array for use in antennas having an active elementsection mountedalongaprincipal axis and designed to operate over apredetermined frequency range;

said active element section having a feed point cou-' pled to a feederharnessat the front end of said active element section, said feederharness coupling all of the active elements to said feed point, theactive elements lying substantially within a plane and extendingoutwardly from and transverse to the principal axis;

said director array being positioned in front of said active section andsaid feed point and being comprised of a first plurality ofsubstantially identical flat conductive plates arranged in spacedparallel fashion and extending outwardly from one side of axis; thespacing between adjacent ones of said first and second plates beingequal and the planes of said plates being perpendicular to the plane inwhich said active elements reside;

the spacing between adjacent plates being in the range from no greaterthan A/lO to no less than M20 where A is the wavelength corresponding tothe highest frequency of the operating frequency range.

12. The director array of claim 11 wherein said conductive plates arespaced apart no greater than M10.

1. A director array for use in antennas having an active element sectionmounted along a principal axis and designed to operate over apredetermined frequency range; said active element section having a feedpoint coupled to a feeder harness at the front end of said activeelement section, said feeder harness coupling all of the active elementsto said feed point, the active elements lying substantially within aplane; said director array being positioned in front of said activesection and said feed point and being comprised of mounting meansaxially aligned with the principal axis of said active element section,and at least first and second substantially flat conductive platessecured to said mounting means and extending in diametrically oppositedirections from the principal axis of said active element section andarranged in staggered spaced parallel fashion, said conductive platesbeing substantially mirror images of one another relative to animaginary plane of symmetry passing through said principal axis and theplanes of said plates being perpendicular to the plane in which saidactive elements reside; the spacing between adjacent plates being in therange from no greater than lambda /10 to no less than lambda /20 wherelambda is the wavelength corresponding to the highest frequency of theoperating frequency range.
 2. The director array of claim 1 wherein saidconductive plates are each tuned to resonate at a frequency near thehigh end of said operating frequency range and being spaced no closerthan lambda /20 wavelengths apart where lambda is the wavelength of theupper end of said frequency range.
 3. The director array of claim 2wherein said conductive plates are spaced apart no greater than lambda/10.
 4. The director array of claim 3 wherein said conductive plates areeach tuned to resonate at a frequency near the high end of saidoperating frequency range and being spaced no closer than lambda /20wavelengths apart where lambda is the wavelength of the upper end ofsaid frequency range.
 5. The director array of claim 1 furthercomprising a support arm for supporting said conductive plates: each ofsaid conductive plates being provided with a pair of mounting arms forpivotally mounting said conductive plates to said support arm; at leastone of said mounting arms having a tapered forward end; a pair ofslightly upwardly bent ears being provided along said support adjacentone of said arms and defining a gap therebetween to embrace the forwardtapered end of said one of said mounting arms and thereby lock saidconductive plate in the operating position.
 6. The array of claim 1wherein each of said plates is a truncated circular disc.
 7. The arrayof claim 1 wherein each of said plates has a substantially rectangularshaped configuration.
 8. The array of claim 1 wherein each of saidplates has a tapered configuration wherein the widest portion thereof isjoined to said support and wherein the narrow end of the tapered platesprojects outwardly from said support.
 9. The array of claim 1 whereinsaid plates are arranged in alternating fashion to lie respectivelyabove and below said principal axis.
 10. The array of claim 1 whereinsaid plates are arranged in alternating fashion to lie respectively tothe left and to the right of said principal axis.
 11. A director arrayfor use in antennas having an active element section mounted along aprincipal axis and designed to operate over a predetermined frequencyrange; said active element section having a feed point coupled to afeeder harness at the front end of said active element section, saidfeeder harness coupling all of the active elements to said feed point,the active elements lying substantially within a plane and extendingoutwardly from and transverse to the principal axis; said director arraybeing positioned in front of said active section and said feed point andbeing comprised of a first plurality of substantially identical flatconductive plates arranged in spaced parallel fashion and extendingoutwardly from one side of the active element section principal axis; asecond plurality of subsTantially identical flat conductive plates beingarranged in spaced parallel fashion and extending outwardly from theopposite side of said principal axis; each of said second plurality ofconductive plates being interspersed with said first plurality ofconductive plates whereby said first and second pluralities form astaggered array along said principal axis; the spacing between adjacentones of said first and second plates being equal and the planes of saidplates being perpendicular to the plane in which said active elementsreside; the spacing between adjacent plates being in the range from nogreater than lambda /10 to no less than lambda /20 where lambda is thewavelength corresponding to the highest frequency of the operatingfrequency range.
 12. The director array of claim 11 wherein saidconductive plates are spaced apart no greater than lambda /10.